DNA sequencing

Abstract

To sequence DNA, DNA samples marked with flourscent infrared dye are applied at a plurality of locations for electrophoresing in a plurality of channels through a gel electrophoresis slab. The channels are scanned with a laser and a sensor, that include a microscope focused on the gel slab. The focal point and slab are adjusted with respect to each other so that the focal point of the microscope remains on the gel slab during a scan. The data from the scan is directly used to amplitude modulate density readings on a display, and the scan is displayed in a horizontal sweep of a cathode ray tube, whereby said cathode ray tube provides intensity displays of bands representing DNA. Different sizes of glass gel sandwiches may be mounted to the same console for different sequencing tasks.

What is claimed is: 
     
       1. Apparatus for sequencing DNA comprising: a gel electrophoresis slab having an upper portion and a lower portion;   means for applying fluorescently marked DNA samples at a plurality of locations for electrophoresing in a plurality of channels through the gel electrophoresis slab;   means for establishing electrical potential across said gel electrophoresis slab wherein DNA samples are resolved in accordance with the size of DNA fragments in said gel electrophoresis slab into fluorescently marked DNA bands;   means for scanning the separated fluorescently marked DNA bands photoelectrically with a laser and a sensor, wherein the laser scans with a scanning light at a scanning light frequency within an absorbent spectrum of said fluorescently marked DNA samples;   means for sensing light at an emission frequency of the marked DNA;   said means for scanning including means for focusing a microscope on the gel portion of the electrophoresis slab, wherein the bands are scanned while still in the gel but after being resolved;   the means for establishing an electrical potential across said gel electrophoresis slab including an upper buffer assembly connected to an upper end of the slab and a lower buffer assembly connected to a lower portion of the gel electrophoresis slab; and   means for positioning the gel electrophoresis slab at any one of a plurality of different elevations, wherein different lengths of gel electrophoresis slabs may be accommodated.   
     
     
       2. Apparatus in accordance with claim 1 in which the means for positioning includes: a support plate within the apparatus for sequencing DNA;   a plurality of side brackets mounted to one of the support plate and gel electrophoresis slab;   a corresponding plurality of pins mounted to the other of the support plate and gel electrophoresis slab, wherein the gel electrophoresis slab may be mounted by the brackets and pins and different elevations.   
     
     
       3. Apparatus according to claim 2 further including: means for electrically connecting at least one of the upper and lower buffer compartments to a source of electricity;   said means for connecting being adapted to connect said source of electricity to a buffer compartment that is at any of a plurality of elevations.   
     
     
       4. Apparatus in accordance with claim 1 wherein light from said laser is in the band incorporating at least the near infrared and infrared regions and said sensor responds to light in the band including at least said near infrared and infrared regions.